Kudzu, Pueraria montana (Lour.) Merr. var. lobata (Willd.) Maesen et S. Almeida (Leguminosae), is an aggressive invasive weed introduced to the United States in the early 20th century for forage and erosion control (Piper 1920). Kudzu turned out to be harmful, causing economic loss and suppressing native plants (Alderman 1998). The USDA removed it from the list of recommended ground cover plants in 1953, and it was listed as a U.S. federal noxious weed in 1998 (U.S. Forest Service 2008). Kudzu infests 7 million acres in the United States (Miller & Edwards 1983; Britton et al. 2000), and kudzu's range in North America is still expanding.
Sun et al. (2006) identified plant pathogens and 116 insect species associated with kudzu in China, and Tayutivutikul & Kushigemati (1992) made a similar survey in the southwestern part of Japan, and noted that 109 insects and 2 spider mites in Japan feed on kudzu. Here we report the first field surveys for kudzu-feeding insects in central Japan (12 sites in the Kinki District, N34°–36°, E135°–137°; 4 sites in Shiga prefecture, 3 sites in Kyoto prefecture, 2 sites in Hyogo prefecture, and 1 site in Osaka and Nara prefecture), and in other regions (7 sites, N31°–42°, E130°– 141°; 1 site in Hokkaido, Miyagi, Toshigi, Shizuoka and Kagoshima prefecture, and 2 sites in Tokyo prefecture).
Timed visual searches in plots with kudzu were conducted from May to Oct in 2004–2005. Three to 6 plots (2–15 m2) were marked per site, and each was searched for 15 min in 2004 and 5 min in 2005. The total time spent searching was 2050 min in the Kinki District and 395 min in other regions. All of different morphotypes found were captured and identified in the laboratory. Immature insects were reared on kudzu at 25°C and 16:8 L:D to obtain adults for identification.
Forty-seven potential kudzu-feeding species were identified during the 2-year survey. Three are new records from kudzu, 28 are previously reported kudzu-feeding species (Tayutivutikul & Kushigemati 1992; Sun et al. 2006), 4 are species without host-plant information, and 12 are species known to feed on fabaceous plants (Inoue 1982; Hayashi et al. 1984; Tomokuni 1993; Anonymous 2006) and included as potential kudzu feeders because kudzu was almost the only fabaceous plant in the research sites.
Of the 47 potential kudzu-feeding species collected, 20 were not listed in Tayutivutikul & Kushigemati (1992; Table 1). Four of these 20 were confirmed as kudzu feeders by our observations and Sun et al. (2006). Further study is needed to determine if the other 16 species are kudzu-feeding specialists. All 5 specialists collected, Trachys auricollis E. Saunders (Buprestidae), 2 cecidomyiids, Pitydiplosis sp. and Genus sp., Mesalcidodes trifidus Pascoe (Curculionidae), and Borowiecius ademptus (Sharp) (Bruchidae), were recorded as such in Tayutivutikul & Kushigemati (1992).
The leaf miner T. auricollis and 2 leaf galler Pitydiplosis sp., and Genus sp. are specialists not reported in Sun et al. 2006, but abundant in Japan. Larvae of M. trifidus form stem galls on kudzu, and cannot complete their development on soybean (Sun et al. 2006). The adults feed on kudzu petioles (Sun et al. 2006) but also on soybean, kidney bean, adzuki bean, and cowpea (Anonymous 2006). The seed-feeder B. ademptus is naturalized in North Carolina (Sun et al. 2006).
Three species of Lepidptera (Endoclyta signifier Walker, Endoclyta excrescens Buutler, and Ostrinia sp.) feed on kudzu roots (Tsugawa & Kayama 1985), 2 of which are hepalid (Endoclyta spp.) generalists and pests of economically important plants (Anonymous 2006).
This project was funded by the USDA Forest Service and the 21st Century COE program for Innovative Food and Environmental Studies Pioneered by Entomomimetic Sciences from the Ministry of Education, Culture, Sports, Science and Technology of Japan. We thank Suzanne Lyon (University of Massachusetts) for critical reading of our manuscript. We thank Kazuo Yamazaki (Osaka City Institute of Public Health and Environmental Science), Kazunori Ohashi, Chihiro Himuro, Shuhei Kada, and Jiichiro Yoshimoto (Kyoto University) for identification of insects.
NEW POTENTIAL KUDZU-FEEDING INSECTS COLLECTED.
Kudzu is an aggressive invasive weed introduced from Japan to the United States. A 2-year survey of herbivorous insects on this plant in central Japan found 47 potential kudzu-feeding species, including 5 likely specialists. The leaf-miner Trachys auricollis is the most promising agent for biological control of kudzu.